I've taken a beer (Tribute or London Pride, so a while back) out of the lounge on a rare occasion. A couple of times I've been in the lounge when there's been a delay, boarding is announced and I've not opened the can yet.

One time I took a can with me just in case the BoB trolley didn't reach me, or it took ages. Thanks to Flyertalk I felt guilty about that and never done it again

Shame T5 doesn't have a nice shop like Centrale that opened recently at Newcastle Central rail station. A massive range of beers there, but there's nowhere in most airports where you can get any sort of beer to take away, never mind a decent beer.

I guess the reason for this is most airlines don't allow consumption of your own alcohol, so airports tend not to sell take away beer.